I have identified a specific sub-species of Zombies:
Labotomized Zombie (Zombius Labotimus)

Characteristics: Has sufficient brain cells working to maintain internal organ functions. Has sufficient brain cells to imitate the living in most scenarios. Does not have sufficient working brain cells to support any but the simplest task, at a given time. Has no powers of reasoning (common sense). Do not leave alone while such a Zombie is "watching a child or invalid".

I think I've worked with several species of that Zombie and didn't realize the full danger.

Thanks for advising us of this widespread danger!